JP2003212617A - Hydraulic substance composition for carbonated hardened body and method for manufacturing carbonated hardened body by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic substance composition for manufacturing a carbonated hardened body by cast molding and a method for making good use of steelmaking slag and stainless steel slag being industrial waste. <P>SOLUTION: This hydraulic substance composition contains a γ-C<SB>2</SB>S-containing substance and a hydraulic substance. This method for manufacturing the carbonated hardened body comprises a step to cast and compact the hydraulic substance composition in a molding flask and a step to age the obtained compact under a gaseous carbon dioxide atmosphere. The carbonated hardened body having a complicated shape can be manufactured. The carbonated hardened body has no crack in it and exhibits excellent strength. This hydraulic substance composition has such an effect that steelmaking slag and stainless steel slag can be used effectively. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a hydraulic substance composition for a carbonation cured body used in the civil engineering and construction industry and a method for producing the carbonation cured body. Parts and% in the present invention are based on mass unless otherwise specified.

[0002]

_2. Description of the Related Art Dicalcium silicate C ₂ S (2CaO.SiO ₂ ) as a kind of calcium silicate
There is. C ₂ S is roughly classified into α-type, β-type, and γ-type polymorphs. Here, the α type is the high temperature phase, and the γ type is the low temperature phase.

Calcium oxide (CaO) and silicon oxide (Si
When a raw material containing O ₂ ) is heat-treated to generate C ₂ S, α-type is changed to β-type and then γ-type in the cooling process, and therefore, it is usually generated as γ-type. In order to obtain α-type or β-type C ₂ S, it is necessary to cool under rapid cooling conditions or to use a mineral stabilizer or the like.

Therefore, among the slags produced as a by-product from a steel mill, converter slag, electric furnace reduction slag, stainless slag, etc. contain γ-type C ₂ S (hereinafter γ-C ₂ S) as a main component.

At this time, the density of γ-type C ₂ S is small, and β
When the mold is transformed into the γ type, a pulverization phenomenon called dusting occurs because of the volume expansion. Dusting is a fatal phenomenon because various slags are used as aggregates such as roadbed materials. In other words, the slag that has generated dusting is cut off from the way of being effectively reused as aggregate, so that the commercial value becomes zero.

For this reason, γ-is used in the slag industry.
C ₂ S has been hated. At present, in order to prevent such dusting, a method of quenching slag, a method of using a mineral stabilizer, etc. have been proposed, but enormous equipment investment is required or expensive addition is required. Since a chemical agent is required, the cost is high in all cases, and a drastic solution has not been reached.

Up to now, a method utilizing converter slag has been proposed. For example, JP-A-49-88922 discloses that the converter slag powder is mixed with 5 to 30% of slaked lime or quick lime, and 5 to 15% of water is added thereto and uniformly mixed, and then 250 kg / cm.
² Pressure molding at 24.5MPa to carbonate, compressive strength 650kg /
A method of manufacturing artificial stone of cm ² (about 64 N / mm ² ) is disclosed.

Further, Japanese Patent Publication No. 56-36147 discloses that a converter slag powder is mixed with Portland cement in an amount of 5 to 30%, and water corresponding to a wet state is added to the mixture to uniformly mix the mixture with 250 kg. A method is disclosed in which a molded product having a compression strength of about 360 to 860 kg / cm ² (about 35 to 84 N / mm ² ) is obtained by pressure molding at a pressure of / cm ² (24.5 MPa) and contacting with carbon dioxide.

However, none of these methods has specified the type of dicalcium silicate contained in the converter slag, and it is necessary to manufacture by pressure molding at a high pressure of about 25 MPa (250 atm). Because there is
There is a problem in that expensive equipment is required and complicated shapes cannot be molded.

Further, in the prior art, in order to maintain the strength of the molded body at a level that can be practically used, it is essential to minimize the amount of kneading water, the fluidity of the kneaded product is insufficient, and casting molding is difficult. It is thought that

Further, in the prior art, the compound composition greatly varies depending on the content of the slag generation step, so that it is effective for the slag generated under a specific manufacturing condition, but it occurs under other manufacturing conditions. There was a problem that it could not handle slag.

Further, γ-C ₂ S is rarely used in the cement industry, which is a user of slag.
This is because γ-C ₂ S has no hydraulic property. Γ-C ₂ S is also disliked in the cement industry, and an attempt to use it as a functional material has not been made so far.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that γ-C ₂ S greatly contributes to the strength enhancement associated with the carbonation treatment.

Further, not only γ-C ₂ S, but also slag which has no effective use because it contains γ-C ₂ S, that is, converter slag, electric furnace reducing slag, stainless slag, and hot metal pretreatment slag. It was also found that such can be used.

Further, these γ-C ₂ S and / or γ-C ₂
By crushing a substance containing S into a fine powder having a specific particle size, pressure molding is unnecessary, and even if a relatively large amount of kneading water that enables cast molding is used, a cured product with high strength can be obtained. The inventors have found that they can be obtained and have completed the present invention.

[0016]

That is, the present invention provides γ-
It is a substance containing C ₂ S and has a Blaine specific surface area.
25 to 90 parts of substances that are 3,000 cm ² / g or more, 75 of hydraulic substances
A hydraulic substance composition for a carbonation-cured product, characterized in that the substance containing γ-C ₂ S is a steelmaking slag and / or a stainless slag. A hydraulic substance composition for a carbonation cured product,
And the content of C ₂ S is 25% or more, gamma-C ₂ contains the S and hydraulic substance, and Blaine specific surface area for the carbonation cured product, which is a 3,000 cm ² / g This is a method for producing a carbonation-cured product, which is a hydraulic substance composition, in which water is added to the hydraulic substance composition to prepare a kneaded product of the hydraulic substance, which is molded and then carbonated.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The γ-C ₂ S of the present invention is obtained by mixing a CaO raw material and a SiO ₂ raw material and heat-treating them. The heat treatment temperature is not particularly limited, but is usually about 1,200 to 1,800 ° C. The cooling method is also not particularly limited. Although rapid cooling is not preferable, special cooling conditions are not necessary and natural cooling is sufficient.

The existence of impurities is not particularly limited, and β-C ₂ S, tricalcium silicate C ₃ S, lankinite C ₃ S ₂ , and / or wollastonite CS may be mixed. .

As the substance containing γ-C ₂ S, the above various slags may be used. Specific examples thereof include stainless slag and steelmaking slag. Steelmaking slag is a general term for converter slag, electric furnace reduction slag, hot metal pretreatment slag, and the like. However, even if the above steelmaking slag or stainless slag does not contain γ-C ₂ S, the effect of the present invention cannot be obtained.

The components of these slags are SiO ₂ , Ca
O, Al ₂ O ₃ , MgO, etc. are the main chemical components, and
_{iO 2, MnO, Na 2 O} , S, P 2 O 5, and Fe ₂ O ₃ and the like.

The compounds contained in the slag include
γ-C₂In addition to S, tricalcium silicate 3CaO ・ SiO
₂, Rankinite 3CaO ・ 2SiO₂, And Wollastonite CaO ・ S
iO₂Calcium silicate, etc., 2CaO ・ Fe₂O₃Calci of etc.
Um ferrite, 12CaO ・ 7Al₂O₃And 3CaO ・ Al₂O₃Cal of etc.
Cium aluminate, Gerenite 2CaO ・ Al₂O₃・ SiO ₂
And akermanite 2CaO ・ MgO ・ 2SiO₂Meliri, a mixed crystal of
Melvinite 3CaO ・ MgO ・ 2SiO₂And monticerite Ca
O ・ MgO ・ SiO₂Calcium magnesium silicate, sulfur etc.
Sulfides such as CaS and CaS and FeS
To (K₂O, Na₂O) ・ Al₂O₃・ SiO₂, Magnetite Fe₃O_Four, Su
Pinel MgO / Al₂O₃, And anorthite CaO ・ Al₂O₃・ 2SiO₂
Etc.

The Blaine specific surface area of the material containing γ-C ₂ S must be 3,000 cm ² / g or more, 4,000cm ² / g~8,
000 cm ² / g is preferred. If the Blaine specific surface area exceeds 8,000 cm ² / g, crushing power is required and it is uneconomical. If the Blaine specific surface area is less than 3,000 cm ² / g, the carbonation-cured product obtained has insufficient strength development and material separation resistance. Can't get

Further, as long as the material contains a gamma-C ₂ S, it was described above, γ-C ₂ S pure material, stainless steel slag, and also be used in place of the iron and steel slag. γ
The content of -C ₂ S is 1 in order to exhibit practical strength.
0% or more is preferable and 20% or more is more preferable.

The amount of the hydraulic substance of the present invention to be used is preferably 10 to 75 parts, more preferably 20 to 50 parts, based on 100 parts in total of the hydraulic substance and the substance containing γ-C ₂ S. If the hydraulic substance is less than 10 parts, the strength of the cured product before carbonation is not sufficient, and the hydrated cured product or the carbonized cured product may be damaged during demolding. If it exceeds, the strength after carbonation may not be sufficient.

[0026] The mixing ratio of the γ-C ₂ S is preferably total from 25 to 90 parts in 100 parts of material containing a hydraulic substance and γ-C ₂ S, and more preferably 50 to 80 parts. If it is less than 25 parts, the strength after carbonation may not be sufficient, and if it exceeds 90 parts, on the contrary, the strength of the cured product before carbonation may be insufficient and the cured product may be damaged during demolding.

As the hydraulic material used in the present invention, various kinds of portland cements such as normal, early strength, super early strength, low heat, and moderate heat are mixed, and various mixture of these portland cements with blast furnace slag, fly ash or silica is mixed. Examples of the cement include filler cement mixed with limestone powder, etc.
Various portland cements such as ultra-rapid high strength, low heat, and moderate heat are more preferable, and one or more of these hydraulic substances can be used.

In the hydraulic substance composition of the present invention, the respective materials may be mixed at the time of kneading, or some or all of them may be mixed in advance.

The particle size of the hydraulic material composition of the present invention is not particularly limited because it depends on the purpose and application to be used, but it is usually 3,000 to 8,000 cm ² / blaine specific surface area value.
g is preferable, and 4,000 to 6,000 cm ² / g is more preferable. 3,00
If it is less than 0 cm ² / g, strength development may not be sufficiently obtained, and if it exceeds 8,000 cm ² / g, workability may deteriorate.

The amount of water used is not particularly limited, but is usually 2 to 100 parts of the hydraulic substance composition of the present invention.
0 to 50 parts is preferable, and 30 to 40 parts is more preferable. If it is less than 20 parts, it may be difficult to cast the kneaded product,
If it exceeds 50 parts, the strength of the cured product immediately after hydration and the carbonized cured product may not be sufficient.

The method of hydrating the hydraulic substance composition of the present invention to form a cured product includes pressure molding, casting,
There are spray molding, centrifugal molding, etc., and casting molding, spray molding, and centrifugal molding are preferable from the viewpoint of work efficiency,
Casting is the most preferable because it can form complex shapes

As the carbonation method, a method of exposing in an atmosphere having a high partial pressure of carbon dioxide, a method of immersing in carbonated water or other water containing carbonate ions or bicarbonate ions, a method of carbonation with CO _{2 in} a supercritical state Can also be considered. Among these methods, the method of exposing in an atmosphere having a high carbon dioxide partial pressure is preferable from the viewpoint of economy and productivity.

As the atmosphere gas, besides carbon dioxide gas, nitrogen, oxygen, water vapor, helium, argon, etc. may be used.
Gases other than carbon dioxide can be mixed and used within a range in which the object of the present invention can be achieved.

The carbon dioxide concentration and pressure in carbonation are not particularly limited, but the carbon dioxide partial pressure calculated from the carbon dioxide concentration and total gas pressure is 0.005 to 1 MPa.
Is preferable, and 0.01-1 MPa is more preferable. When the partial pressure of carbon dioxide is less than 0.005 MPa, the rate of carbonation is slow and it is uneconomical. Further, when the total gas pressure and / or the carbon dioxide partial pressure exceeds 1 MPa, an expensive pressure vessel is required.

The humidity in carbonation is not particularly limited, but is preferably 40% to 90% and 60 to 90%.
85% is more preferable. If the humidity is lower than 40%, the rate of carbonation is slow and it is uneconomical, and if it exceeds 90%, dew condensation occurs and the surface is corroded, and the appearance of the product deteriorates.

The temperature for carbonation is not particularly limited, but the temperature range for carbonation is
20-60 degreeC is preferable and 25-40 degreeC is more preferable. If it is lower than 20 ° C, the carbonation rate is slow, and if it exceeds 60 ° C, cracks are likely to occur when returning to room temperature.

In the present invention, in addition to a hydraulic substance and a substance containing γ-C ₂ S, an aggregate such as sand and gravel, a water reducing agent, an AE water reducing agent, a high performance water reducing agent, a high performance AE water reducing agent, Antifoaming agent, foaming agent, thickener, rust preventive, antifreeze, shrinkage reducing agent, polymer emulsion, setting regulator, clay mineral such as bentonite, and additives such as anion exchangers such as hydrotalcite One or more of them can be used within a range that does not substantially impair the object of the present invention.

In the present invention, the method of mixing the respective materials is not particularly limited, and the respective materials may be mixed at the time of construction, or some or all of them may be mixed in advance.

As the mixing device, any existing device can be used. For example, a tilt cylinder mixer, an omni mixer,
A Henschel mixer, a V-type mixer, a Nauta mixer or the like can be used.

[0040]

EXAMPLES The present invention will be further described below based on experimental examples of the present invention.

Experimental Example 1 25 parts of cement and various inorganic powders (γ-C
₂ S, slags A to F, and 75 parts of limestone powder) were mixed to prepare a hydraulic material composition. To 100 parts of this hydraulic material composition, 30 parts of water was added and kneaded to prepare a paste. This paste was poured into a mold, and after 24 hours, it was demolded, and then cured at 20 ° C in water for 6 days until the age of 7 days (hereinafter referred to as pre-curing). Then, 30 ℃, relative humidity
Accelerated carbonation in an environment of 60% and 5% carbon dioxide concentration (hereinafter referred to as carbonation curing). The compressive strength of the sample was measured, and cracks and the like of the sample were also observed. For comparison, the same experiment was performed for the case where the underwater curing was continued after the completion of the precuring (hereinafter referred to as standard curing). The results are also shown in Table 1.

<Material used> Cement: Early Strength Portland Cement, Electrochemical Industry
Company γ-C₂S: Reagent calcium carbonate 2 mol and silica dioxide
Raw material obtained by mixing and pulverizing 1 mol of elementary metal in an electric furnace at 1500 ° C for 3 hours
After firing, it is taken out of the furnace and air-cooled (gradual cooling) for synthesis.
Further crushed to a brane specific surface area of 4,000 cm²/ g. Slag A: Converter slag, slowly cooled product, CaO content 40%, SiO₂Including
Content 13%, MgO content 10%, Al₂O₃Content 3%, Fe₂O₃Content 1
0%, FeO content 17%, γ-C₂S content 37%, 2CaO ・ F
e₂O₃, Free lime, free magnesia as the main component. Blur
Specific surface area 4,000 cm²/ g. Slag B: Electric furnace reduction slag, CaO content 52%, SiO₂Including
27%, Al₂O₃Content 11%, MnO content 5%, MgO content 0.5
%, S content 0.5%, γ-C₂66% S content, CaO / Si
O₂, And 12CaO ・ 7Al₂O₃Mainly composed of solid solution. Brae
Specific surface area 4,000 cm²/ g. Slag C: Stainless slag, CaO content 52%, SiO₂Inclusion
Amount 28%, MgO content 10%, Al₂O₃Content 7%, Cr₂O₃Content 1
%, Na₂O content 0.5%, γ-C₂79% S content, Melv
Innite 3CaO ・ MgO ・ 2SiO₂, 12CaO / 7Al₂O₃Solid solution, free
The main component is magnesia. Blaine specific surface area 4,000 cm²
/ g. Slag D: Hot metal pretreatment slag (decarburized slag), CaO included
Content 46%, SiO₂Content 12%, Al₂O₃1.4% content, MnO content
6%, total Fe content 18%, MgO content 8%, γ-C₂S content 34
%, 2CaO / Fe₂O₃, Free magnesia as the main component. Blur
Specific surface area 4,000 cm²/ g. Slag E: Converter slag, quenched product, CaO content 40%, SiO₂Including
Content 13%, MgO content 10%, Al₂O₃Content 3%, Fe₂O₃Content 1
0%, FeO content 17%, β-C₂S-containing, 2CaO / Fe
₂O₃, Free lime, free magnesia as the main component. Blur
Specific surface area 4,000 cm ²/ g. Slag F: Granulated blast furnace slag, vitreous, CaO content 42%,
SiO₂34% content, Al₂O₃Content 14%, Fe₂O₃Content 0.2%, Mg
O content 7%. Blaine specific surface area 4,000 cm²/ g. Limestone fine powder: The main component is calcium carbonate. Blaine ratio table
Area 4,000 cm²/ g. Water: Tap water

<Measurement method> Compressive strength: 2 × 2 × 8 cm Test piece was prepared and measured. Neutralization depth: 2 × 2 × 8 cm Specimen is cut into a circle, and the cross-section is coated with phenolphthalein alcohol solution to confirm the neutralization depth, and the completely neutralized specimen is carbonated and cured. It was used as a later specimen. The results are shown in Table 1.

[0044]

[Table 1] ○: No cracks, △: Some cracks, ×
Has many cracks. The compressive strength-is not evaluated because it cannot be measured or a large number of cracks are generated in the carbonized cured product.

Experimental Example 2 Similar to Experimental Example 1 except that γ-C ₂ S was used as the inorganic powder and the mixing ratio of γ-C ₂ S in the hydraulic composition was changed as shown in Table 2. Went to. The results are shown in Table 2.

[0046]

[Table 2] ◯ of the test piece has no cracks, × has many cracks,
* Cannot be prepared because it does not cure. The compressive strength-is not evaluated because it cannot be measured or a large number of cracks are generated in the carbonized cured product.

Experimental Example 3 γ-C ₂ S was used as the inorganic powder, and the blending ratio of γ-C ₂ S in the hydraulic composition was 25 parts, and the Blaine specific surface area of γ-C ₂ S is shown in Table 3. The same procedure as in Experimental Example 1 was performed except that the change was made as shown in FIG. The results are shown in Table 3.

[0048]

[Table 3] ○ in the “State of specimen” column indicates no crack.

Experimental Example 4 γ-C ₂ S having a Blaine specific surface area of 4,000 cm ² / g as an inorganic powder
Was used, and the mixing ratio of water and the hydraulic substance (water / hydraulic substance composition ratio, W / C ratio) was changed as shown in Table 4, and the same procedure as in Experimental Example 1 was performed. The results are shown in Table 4.

[0050]

[Table 4] ◯ of the test piece is not cracked, and Δ is slightly cracked. The compressive strength-is not evaluated because it cannot be measured or a large number of cracks are generated in the carbonized cured product.

[0051]

EFFECTS OF THE INVENTION By using the hydraulic substance composition of the present invention, a cured product which can be cast by casting, exhibits excellent strength development in carbonation curing, and does not cause cracks can be obtained. In addition, converter slag, electric furnace reduction stage slag, stainless slag, which has not been used effectively until now,
The effect of effectively using the hot metal pretreatment slag or the like is also obtained.

Claims (4)

[Claims] 1. A substance containing γ-C ₂ S and having a Blaine specific surface area of 3,000 cm ² / g or more is 25 to 90.
Parts, and 75 to 10 parts of a hydraulic substance, a hydraulic substance composition for a carbonation-cured product. 2. The hydraulic substance composition for a carbonation-cured product according to claim 1, wherein the substance containing γ-C ₂ S is steelmaking slag and / or stainless slag. 3. The content of γ-C ₂ S is 25 to 90%, and γ-
A hydraulic substance composition for a carbonation-cured product, which contains C ₂ S and a hydraulic substance and has a Blaine specific surface area of 3,000 cm ² / g. 4. A carbonic acid characterized by comprising adding water to the hydraulic substance composition according to claim 1 to prepare a kneaded product of the hydraulic substance, molding and then carbonating. Chemically cured product manufacturing method.